1. Field of the Invention
This invention relates to a heat-sensitive transferring recording medium used for heat-sensitive transferring recording apparatuses such as thermal facsimile, thermal printer and the like.
2. Description of the Prior Art
Heat-sensitive recording system which is of non-impact type has recently drawn attention since the system is free of noise and can be easily handled.
Indeed, conventional heat-sensitive recording systems are free of noise and neither development nor fixation of the images is necessary and, in addition, the handling is easy, but the resulting record is liable to be falsified and its durability is not so good.
For the purpose of solving these drawbacks, a particular heat-sensitive transferring recording method was proposed. That is, a heat melting layer is provided on a substrate, and said ink layer is contacted with a receiving paper (recording paper) followed by heating with a thermal head through the substrate to melt said ink layer resulting in transferring of the heated portion to a receiving paper which is an ordinary paper.
The above-mentioned heat-sensitive transferring recording method can give good printed letters where the smoothness of the receiving paper which is an ordinary paper is high, but where the smoothness is low, for example, the Bekk smoothness test value is not higher than 50 sec., the heat melting ink layer contacts the receiving paper at some portion while said layer does not contact the receiving paper at other portions, because of the uneven surface of the receiving paper. This results in a low transferring effeciency, formation of void, and low sharpness. In addition, since the heat melting ink has a high fluidity, the ink penetrates into the inside of the receiving paper so that the density of the printed letters is low and good printed letters can not be obtained.
In conventional ink manufacturing methods, a hot melt type coating material or an organic solvent type coating material is used and the content of resin components is at most 20% by weight. In the case of hot melt ink, the more the content of resin component, the higher is the melt viscosity, and thereby coating is not possible.
In the case of organic solvent type inks, it is difficult to dissolve or disperse waxes and, further, remove the organic solvent from the wax dissolved or dispersed in the organic solvent for drying.